The general form is:

if(b)
{
	action,b is true
}
else
{
	action.b is false
}

Where b is anything or expression that should be a boolean value.

if(condition)
statement1;
else
statement2;

Here each statement may be a single statement or compound statement enclosed in a block. The condition is any expression that returns a Boolean value and else part is optional. The mechanism is if the condition is true, then statement1 is executed, otherwise statement2 will be executed. Consider an example :

class IfElseDemo
{
	public static void main(String args[ ])
	{
		int x=15;
		if(x<20)
		System.out.println("JavaRace");
		else
		System.out.println("JavaExcellence");
	}
}

Download Code
Output
JavaRace

There may be a situation when we need to execute a block of code several number of times, and is often referred to as a loop. A loop is defined as the repetition of instruction till the condition is satisfied.

class IfElseDemo1
{
	public static void main(String[] args)
	{
		int x=0;
		if(x)
		{
			System.out.println("Silan Software");
		}
		else
	 	{
		 	System.out.println("JavaRace");
	 	}
	}
}

Output

Compilation Error: incompitible types
found : int
required : boolean

class IfElseDemo2
{
	public static void main(String[]args)
	{
		int x=10;
		if(x=20)
	{
		System.out.println("Silan Software");
	}
		else
	{
		System.out.println("JavaRace");
	}
}

Output

Compilation Error

Compilation Error: incompitible types
found : int
required : boolean

let's see some other example for better clarity:

1. intx=50;
if(x==50)
{
	s.o.p("Hi");
}
else
{
	s.o.p("Hello");
}

Output:
Hi

2. boolean b=false;
if(b)
{
	s.o.p("Hi");
}
else
{
	s.o.p("Hello");
}

Output:
Hello

3. boolean b=false;
if(b==false)
{
	s.o.p("Hi");
}
else
{
	s.o.p("Hello");
}

Output:
Hi